Genetic Epidemiology of Causal Variants Across the Life Course is submitted in response to RFA HG-07-014, as a consortium of well characterized population based studies and a central genotyping and resequencing core laboratory, to accelerate the understanding of the role and population impact of putative causal genetic variants related to complex diseases. This collaborative network includes six of the most informative and demographically diverse population-based studies extant, contributing approximately 58,000 men and women from the main ethnic and racial groups in the U.S., ranging in age from childhood to old adulthood. Those examined in the six studies are extensively characterized for a wide range of phenotypes and traits, and five studies have immediately available stored DNA of high quality for transfer to the core laboratory. The participating studies include population based cohorts with repeat examinations and long term follow up and a national probability sample, with clinical and subclinical measurements on a range of health conditions, their precursors and natural history, characterized across the life course. This collaborative network is designed to provide optimal capabilities to estimate and replicate associations of genetic variants with complex diseases in diverse U.S. populations, in individual and environmental contexts of public health relevance, with power sufficient to identify associations, interactions, and population impact in subgroups. The team of investigators contributes epidemiologic, genetic, methodologic and subject-matter expertise and a demonstrated record of productivity in collaborative, interdisciplinary settings. The network builds on existing capabilities and the proven administrative channels of the assembled partner studies for efficient and timely access to phenotypic, exposure and contextual data, for analyses within each partner study and for replication across studies, and for rapid sharing of the resulting descriptive and association data. The investigators will serve as effective collaborators within the wider study, contributing methodologic innovation and analytic support and serving on committees and working groups set up by the Steering Committee. The collaborative resource assembled in this application will permit the estimation of the role and population impact of selected genetic variants in diversity-based populations, for an array of chronic diseases, their risk factors and intermediate outcomes, at different life epochs, and for groups defined by potentially modifiable contexts. Genomic assays will be conducted as needed to further characterize the reported associations.